As a second year high school chemistry student, I still have a vivid memory of my excitement when I first saw a chart of the periodic table of elements. The order in the universe seemed miraculous, and I wanted to study and learn as much as possible about the natural sciences.

For the sake of persons of ... different types, scientific truth should be presented in different forms, and should be regarded as equally scientific, whether it appears in the robust form and the vivid coloring of a physical illustration, or in the tenuity and paleness of a symbolic expression.

I can remember … starting to gather all sorts of things like rocks and beetles when I was about nine years old. There was no parental encouragement—nor discouragement either—nor any outside influence that I can remember in these early stages. By about the age of twelve, I had settled pretty definitely on butterflies, largely I think because the rocks around my home were limited to limestone, while the butterflies were varied, exciting, and fairly easy to preserve with household moth-balls. … I was fourteen, I remember, when … I decided to be scientific, caught in some net of emulation, and resolutely threw away all of my “childish” specimens, mounted haphazard on “common pins” and without “proper labels.” The purge cost me a great inward struggle, still one of my most vivid memories, and must have been forced by a conflict between a love of my specimens and a love for orderliness, for having everything just exactly right according to what happened to be my current standards.

I took a glass retort, capable of containing eight ounces of water, and distilled fuming spirit of nitre according to the usual method. In the beginning the acid passed over red, then it became colourless, and lastly again all red: no sooner did this happen, than I took away the receiver; and tied to the mouth of the retort a bladder emptied of air, which I had moistened in its inside with milk of lime lac calcis, (i.e. lime-water, containing more quicklime than water can dissolve) to prevent its being corroded by the acid. Then I continued the distillation, and the bladder gradually expanded. Here-upon I left every thing to cool, tied up the bladder, and took it off from the mouth of the retort.— I filled a ten-ounce glass with this air and put a small burning candle into it; when immediately the candle burnt with a large flame, of so vivid a light that it dazzled the eyes. I mixed one part of this air with three parts of air, wherein fire would not burn; and this mixture afforded air, in every respect familiar to the common sort. Since this air is absolutely necessary for the generation of fire, and makes about one-third of our common air, I shall henceforth, for shortness sake call it empyreal air, [literally fire-air] the air which is unserviceable for the fiery phenomenon, and which makes abut two-thirds of common air, I shall for the future call foul air [literally corrupted air].

In the temple of science are many mansions, and various indeed are they that dwell therein and the motives that have led them thither. Many take to science out of a joyful sense of superior intellectual power; science is their own special sport to which they look for vivid experience and the satisfaction of ambition; many others are to be found in the temple who have offered the products of their brains on this altar for purely utilitarian purposes. Were an angel of the Lord to come and drive all the people belonging to these two categories out of the temple, the assemblage would be seriously depleted, but there would still be some men, of both present and past times, left inside. Our Planck is one of them, and that is why we love him.

In this model, the sun is a very tiny speck of dust indeed—a speck less than a three-thousandth of an inch in diameter ... Think of the sun as something less than a speck of dust in a vast city, of the earth as less than a millionth part of such a speck of dust, and we have perhaps as vivid a picture as the mind can really grasp of the relation of our home in space to the rest of the universe.

It is not enough to teach man a specialty. Through it he may become a kind of useful machine, but not a harmoniously developed personality. It is essential that the student acquire an understanding of and a lively feeling for values. He must acquire a vivid sense of the beautiful and of the morally good. Otherwise he—with his specialized knowledge—more closely resembles a well-trained dog than a harmoniously developed person.

It is not improbable that some of the presentations which come before the mind in sleep may even be causes of the actions cognate to each of them. For as when we are about to act [in waking hours], or are engaged in any course of action, or have already performed certain actions, we often find ourselves concerned with these actions, or performing them, in a vivid dream.

In Mortimer Jerome Adler, Charles Lincoln Van Doren (eds.) Great Treasury of Western Thought: A Compendium of Important Statements on Man and His Institutions by the Great Thinkers in Western History (1977), 352

It is therefore easy to see why the churches have always fought science and persecuted its devotees. On the other hand, I maintain that the cosmic religious feeling is the strongest and noblest motive for scientific research. Only those who realize the immense efforts and, above all, the devotion without which pioneer work in theoretical science cannot be achieved are able to grasp the strength of the emotion out of which alone such work, remote as it is from the immediate realities of life, can issue. What a deep conviction of the rationality of the universe and what a yearning to understand, were it but a feeble reflection of the mind revealed in this world, Kepler and Newton must have had to enable them to spend years of solitary labor in disentangling the principles of celestial mechanics! Those whose acquaintance with scientific research is derived chiefly from its practical results easily develop a completely false notion of the mentality of the men who, surrounded by a skeptical world, have shown the way to kindred spirits scattered wide through the world and through the centuries. Only one who has devoted his life to similar ends can have a vivid realization of what has inspired these men and given them the strength to remain true to their purpose in spite of countless failures. It is cosmic religious feeling that gives a man such strength. A contemporary has said, not unjustly, that in this materialistic age of ours the serious scientific workers are the only profoundly religious people.

Let me tell you how at one time the famous mathematician Euclid became a physician. It was during a vacation, which I spent in Prague as I most always did, when I was attacked by an illness never before experienced, which manifested itself in chilliness and painful weariness of the whole body. In order to ease my condition I took up Euclid’s Elements and read for the first time his doctrine of ratio, which I found treated there in a manner entirely new to me. The ingenuity displayed in Euclid’s presentation filled me with such vivid pleasure, that forthwith I felt as well as ever.

Long before I ever saw the desert I was aware of the mystical overtones which the observation of nature made audible to me. But I have never been more frequently or more vividly aware of them than in connection with the desert phenomena.

Looking back … over the long and labyrinthine path which finally led to the discovery [of the quantum theory], I am vividly reminded of Goethe’s saying that men will always be making mistakes as long as they are striving after something.

One of the grandest figures that ever frequented Eastern Yorkshire was William Smith, the distinguished Father of English Geology. My boyish reminiscence of the old engineer, as he sketched a triangle on the flags of our yard, and taught me how to measure it, is very vivid. The drab knee-breeches and grey worsted stockings, the deep waistcoat, with its pockets well furnished with snuff—of which ample quantities continually disappeared within the finely chiselled nostril—and the dark coat with its rounded outline and somewhat quakerish cut, are all clearly present to my memory.

Our first endeavors are purely instinctive prompting of an imagination vivid and undisciplined. As we grow older reason asserts itself and we become more and more systematic and designing. But those early impulses, though not immediately productive, are o

The moment after, I began to respire 20 quarts of unmingled nitrous oxide. A thrilling, extending from the chest to the extremities, was almost immediately produced. I felt a sense of tangible extension highly pleasurable in every limb; my visible impressions were dazzling, and apparently magnified, I heard distinctly every sound in the room and was perfectly aware of my situation. By degrees, as the pleasurable sensations increased, I last all connection with external things; trains of vivid visible images rapidly passed through my mind, and were connected with words in such a manner, as to produce perceptions perfectly novel. I existed in a world of newly connected and newly modified ideas. I theorised—I imagined that I made discoveries. When I was awakened from this semi-delirious trance by Dr. Kinglake, who took the bag from my mouth, indignation and pride were the first feelings produced by the sight of the persons about me. My emotions were enthusiastic and sublime; and for a minute I walked round the room, perfectly regardless of what was said to me. As I recovered my former state of mind, I felt an inclination to communicate the discoveries I had made during the experiment. I endeavoured to recall the ideas, they were feeble and indistinct; one collection of terms, however, presented itself: and with the most intense belief and prophetic manner, I exclaimed to Dr Kinglake, 'Nothing exists but thoughts!—the universe is composed of impressions, ideas, pleasures and pains!'

The poetic beauty of Davy's mind never seems to have left him. To that circumstance I would ascribe the distinguishing feature in his character, and in his discoveries,—a vivid imagination sketching out new tracts in regions unexplored, for the judgement to select those leading to the recesses of abstract truth.

The study of … simple cases would, I think, often be of advantage even to students whose mathematical attainments are sufficient to enable them to follow the solution of the more general cases. For in these simple cases the absence of analytical difficulties allows attention to be more easily concentrated on the physical aspects of the question, and thus gives the student a more vivid idea and a more manageable grasp of the subject than he would be likely to attain if he merely regarded electrical phenomena through a cloud of analytical symbols.

To day we made the grand experiment of burning the diamond and certainly the phenomena presented were extremely beautiful and interesting… The Duke’s burning glass was the instrument used to apply heat to the diamond. It consists of two double convex lenses … The instrument was placed in an upper room of the museum and having arranged it at the window the diamond was placed in the focus and anxiously watched. The heat was thus continued for 3/4 of an hour (it being necessary to cool the globe at times) and during that time it was thought that the diamond was slowly diminishing and becoming opaque … On a sudden Sir H Davy observed the diamond to burn visibly, and when removed from the focus it was found to be in a state of active and rapid combustion. The diamond glowed brilliantly with a scarlet light, inclining to purple and, when placed in the dark, continued to burn for about four minutes. After cooling the glass heat was again applied to the diamond and it burned again though not for nearly so long as before. This was repeated twice more and soon after the diamond became all consumed. This phenomenon of actual and vivid combustion, which has never been observed before, was attributed by Sir H Davy to be the free access of air; it became more dull as carbonic acid gas formed and did not last so long.

Entry (Florence, 27 Mar 1814) in his foreign journal kept whilst on a continental tour with Sir Humphry Davy. In Michael Faraday, Bence Jones (ed.), The Life and Letters of Faraday (1870), Vol. 1, 119. Silvanus Phillips Thompson identifies the Duke as the Grand Duke of Tuscany, in Michael Faraday, His Life and Work (1901), 21.

When the pioneer in science sets forth the groping feelers of his thought, he must have a vivid, intuitive imagination, for new ideas are not generated by deduction, but by an artistically creative imagination.

In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.
(1987) -- Carl Sagan